Cognitive control over perception, thought, and action allows us to stay on task by keeping irrelevant information at bay. Whether control is successful or not largely depends on its dynamic properties. It needs to respond promptly to upcoming challenges, such as the need for flexible change, or to critical triggering events, such as the experience of conflict, but it also needs to be able to profit from past control events. Deficits i dynamic control are linked to prevalent clinical disorders, including attention deficit/hyperactiviy disorder, schizophrenia, or depressive symptoms. Moreover, control dynamics change across the adult life span in ways that are not well understood and that become particularly relevant in multi-tasking situations. In order to fully understand both intact and deficient control we need to track how the dynamics of control actually unfold over time. One central claim of this application is that eye tracking combined with adequate experimental paradigms and analytic techniques can provide dynamic information with the necessary precision. With these analytic tools, we examine here the general hypothesis that local control dynamics are profoundly affected global control settings. Specifically, we propose that control operates either in a maintenance mode, emphasizing stable behavioral patterns, or in an updating mode, emphasizing flexible change. Furthermore, we hypothesize that older adults' specific difficulties in multi-tasking situations arise from on overuse of the updating mode, which in turn has pervasive down-stream effects on local control phenomena. Using our eye-tracking based analytic tools; we test these general hypotheses in three different ways. First, we look at the precise short-term and longer-term temporal dynamics of adopting attentional settings and how these dynamics change as a function of control modes and age. Second, we examine for the first time how exactly interruptions affect cognitive activity in young and old adults. Third, we use eye-movements to directly assess when individuals engage in updating, thus allowing us to determine both antecedents and consequences of updating operations, as well as why older adults often dramatically over-engage in updating. Thus, this work addresses substantive questions about flexible control of thought and action and about the nature of age differences therein, but also brings a new set of methodological tools to the study of control. These tools will substantially enhance the precision with which researchers can capture the dynamic nature of control. Multitasking and interruptions are an omnipresent reality in the way we use modern digital media. Difficulties with multitasking in older adults contribute to the emerging digital divide, potentially constraining seniors' societal participation or access to important health-care tools. The information gained in this project will be useful for the design of multi-task environments or targeted training procedures.